Plumbite solution



Patented Nov. '7, li g 'IPHJEUMBII'EE SQPLUTL'GEN Joseph E. llllrapean, .llia, Elaond, Ind, agnor to The Glidden @ompany, Cleveland, @liio, a corporation of (Ethic No meme. Application any as, was, Serial No. 32,931

(m. eta-=1) This invention relates to plumbite solutions of When litharge is treated with caustic soda sothe type formed by dissolving lead oxide in lution at 20 0,, a solution of 3.5 grams per 100 caustic alkalies, and has particular reference grams of solution can be obtained. If the temto new plumbite solutions and the process of perature be increased, the solubility becomes 5 producing them, which comprises dissolving the greater, the following table indicating the solu- 5 lead oxide in caustic alkali solution in the presbilities of litharge in 20 Baum caustic soda soenoe of an agent which retards crystallization of lution, solubilities being expressed as grams lead oxide from the solutions. More particularly, litharge per 100 grams of solution. it refers to plumbite solutions in which crystallization of lead oxide is retarded by the use of a TABLE I" SIummy of mharge at nous 10 water-soluble polyhydroxy organic compound. temperatures Sodium plumbite, and other alkali plumbites, have been much used as doctor solutions for Temperature Solubility the removal of sulphur in the refining of petroleum oils. The solutions, are ordinarily made 3.5 15 by dissolving litharge in a caustic soda solution; :3 and as a matter of conventional prior art pracc 5.6 tice, the solutions generally comprise 3.5 grams $308 9g of litharge in 100 grams of Baum caustic 90 0:

b soda solution, this being a saturated solution 20 at about 20 C.

In order to reduce the cost of the refining op- When litharge is treated with hot caustic solueration, which depends largely on the lead contion, easy solubility is thus obtained, but as the tent of the treating solution, it has been sugtemperature drops, crystallization occurs if too 5" gested that the concentration of lead in the much litharge has been added.

caustic soda solution be increased by using bat- If there be added to the litharge various addiy r p, r a e so as to convert he antition agents, there is no change in the solubility at monial lead of d Scrap lith -rs c tai any given temperature. The following table illead antimoniate (Kirk, United States Patent l strates this point:

1,977,993, October 23, 1934). This treatment 30 does increase the lead solubility to a considerable TABLE n-SZub1l1ty f g plus addition degree, doubling the solubility, and permitting agents at 20 solutions containing 7.0 grams litharge per 100 grams of 20 Baume caustic soda to be made. solubility in s.- This method, however, introduces inerts such as Gm 100 grams 00 lead sulphate and lead carbonate into the caustic t se Adam agent Baum caustic soda solution to the extent of about 4-6%, causing carbonation of the caustic solution and sludgm o N 3 mg of the insoluble inerts- AS a result, caustic is 1030 c.5t5555331313132233::::::::::"": a 45 40 lost; and it is necessary to filter ofi the sludge. tl irtaric acidh 40 I have discovered that apparently increased 1 Z g 1 solubility of the litharge can be obtained, with- 10.0 0.;5 NaKtartratau 3.35. out the necessity for adding large quantities of mo m made by Pmess impurities, by adding to the solution a small I quantity of a catalyst of the class of water- If, however, the same procedure asused for Ta- 45 soluble polyhydroxy organic compounds. I have ble ll be followed out, except that the litharge further investigated this apparently increased be treated at 100 C., and cooled to 20 C., the solubility and have discovered that the effect is caustic soda solutions contain considerably highnot an increase in solubility, but the production er percentages of litharge, as indicated in Table of stable super-saturated solutions. 50

Solubility in Grams 100 grams 20 litharge Addltlon agent Baumdcaustic so a 3. 5 3. 7. 0 3. 10. 0 3. 00 3. 5 2. 95 7. 0 6. 25 10. 0 d 6. 10.0 0. 4.76 10. 0 0.10 tartaric acid 6. 25 10. 0 0.25 tartaric acid 6. 40 1D. 0 0.10 gIyccroL 6.00 10. 0 0.10 dextrose" 5.80 10. 0 0.25 dextrose. 6. 00 10. 0 0.10 sucrose. 6. 30 10. 0 0.25 sucrose- 6. 10. 0 0.125 sucrose. 6. 45 10.0 0.25 hydroquinina. 5. 65 10. 0 0.025 hydroquinina 4.05 10. 0 0.25 NaK tartrate 5. 40 10. 0 0.15 starch 2. 95 10. 0 0.15v paper fiber- 3. 05 10. 0 0.10 starch 3. 90

I believe, the action of these agents, therefore,v

to be that of preventing crystallizatiom'by stabilizing the super-saturated solution of lead oxide in caustic soda.

It will be noted that all of the addition agents 7 do not work; I attribute this to the fact that they are not water-soluble, even the so-called soluble starch being merely a colloidal dispersion in water.

The addition agents may be added by mixing,

caustic is eliminated, and there is no sludge to remove when the doctor solution is prepared.

Another advantage of the use of my addition agents lies in the fact that they inhibit crystallization 'of' litharge on sudden temperature changes. Thus, a. doctor solution, saturated at 20 0., if exposed to low temperatures would deposit litharge in pipe lines, tanks, etc.; while a similar solution containing one of my addition agents would retain the litharge in super-saturated solution.

While I have indicated certain preferred concentrations of caustic soda solution, changes can be made without departing from the spirit of my invention. Similarly, the lead may enter the plumbite solution from some source other than litharge; and I consider the other alkali hydroxides chemical equivalents of the caustic soda for the purpose of making plumbite solutions.

The amounts of addition agent ca n be varied considerably, as indicated in Table III. creased lead content can be obtained by the use of as low as 0.25% tartaric acid, or hydroquinine; and I have used as high as 5.0% 'in'some' cases,

although in all of my experiments maximumef-' fect has been obtained at or below 3%.

I claim:

1. A sodium plumbite doctor solution containing a higher percentage of sodium plumbite than can normally be maintained in aqueous solution under the same conditions comprising a solution of litharge in an excess of caustic soda over that necessary to form sodium' plumbite with the litharge, and between 0.25% and 5%, based on the litharge content, of a water soluble polyhydroxy compound selected from the class consisting of water soluble polyhydroxy acids, water soluble salts of polyhydroxy acids in which the cations consist of monovalent ions. water soluble polyhydroxy alcohols, water soluble polyhydroxy phenols and water soluble saccharoses.

2. The composition of claim 1 in which the percentage of the water soluble polyhydroxy compound is 3% or less of the litharge content.

3. The composition of claim 1 in which the water soluble polyhydroxy compound is a water soluble saccharose.

. 4. The composition of claim 1 in which the water soluble polyhydroxy compound is a water soluble polyhydroxy alcohol.

5. The composition of claim 1 in which the water soluble polyhydroxy compound is a water soluble polyhydroxy phenol.

JOSEPH E. DRAPEAU, JR. 

